If you are still looking for these items, I hope you understand that they are reportedly different sounding amps. The TTVJ Slim was developed to replace a portable tube amp made by TTVJ and so it has a warmer sounding characteristic that mimics the tube qualities of its predecessor. The Arrow 4G takes its tuning similarly from it's previous iterations, which is of a neutral, uncolored sound characteristic. I am also in the market for both amps, and probably will be getting both new after the summer, but they are supposedly very different in terms of sound from each other.